Fields, principal branches, and areas of application
Electronics comprises three fields of research: vacuum electronics, solid-state electronics, and quantum electronics. Each field is subdivided into a number of branches and a number of areas of application. A branch combines groups of like physiochemical phenomena and processes that are of fundamental importance to the development of many classes of electronic devices in a given area. An area of application encompasses not only the methods of designing and constructing electronic devices that are similar in operating principle or function but also the techniques used in the devices’ manufacture.
Vacuum electronics. Vacuum electronics includes the following branches: (1) emission electronics, which encompasses thermionic emission, photoemission, secondary emission, and field emission, as well as problems of cathodes and antiemission coatings; (2) the formation and control of electron and ion fluxes; (3) the formation of electromagnetic fields with resonators, resonator systems, slow-wave circuits, and power input and output devices; (4) electronoluminescence, or cathodoluminescence; (5) the physics and technology of high vacuums, that is, the production, maintenance, and monitoring of high vacuums; (6) thermal processes such as vaporization in a vacuum, deformation of parts under cyclic heating, surface breakdown of metals under pulsed heating, and heat discharge of equipment components; (7) surface phenomena associated with the formation of films on electrodes and insulators and of irregularities on electrode surfaces; (8) surface-treatment technology, which includes treatment with electron beams, ions, and lasers; and (9) gas media, a branch that includes aspects of the production and maintenance of optimal gas composition and pressure in gas discharge devices.
The principal areas of application of vacuum electronics encompass aspects of the development of various electron-tube devices. These devices include such vacuum tubes as triodes, tetrodes, and pentodes; such microwave tubes as magnetrons and klystrons; such electron-beam devices as picture tubes and oscillograph tubes; such photoelectric devices as phototubes and photomultipliers; X-ray tubes; and such gas-discharge devices as high-power rectifiers, light sources, and indicators.
Solid-state electronics. The branches and areas of application of solid-state electronics are associated primarily with semiconductor electronics. The principal branches of semiconductor electronics are the following: (1) the study of the properties of semiconductor materials and the effects of impurities on those properties; (2) the creation of areas of differing conductivity on a single crystal by means of epitaxy (see), diffusion, ion implantation, or irradiation of semiconductor structures; (3) the application of dielectric and metallic films on semiconductor materials and the development of the technology for fabricating films with the necessary properties and configurations; (4) the investigation of the physical and chemical processes that occur on semiconductor surfaces; and (5) the development of methods and equipment for producing and measuring microelements that are a few micrometers or less in size.
The basic areas of application of semiconductor electronics are associated with the development and manufacture of various types of semiconductor devices. Such devices include semiconductor diodes (rectifier, mixer, parametric, and avalanche diodes), amplifier and oscillator diodes (tunnel, avalanche transit time, and Gunn diodes), transistors (bipolar and unipolar), thyristors, optoelectronic devices (light-emitting diodes, photo-diodes, phototransistors, optrons, and light-emitting-diode and photodiode matrices), and integrated circuits.
The areas of application of solid-state electronics also include dielectric electronics, magnetoelectronics, acoustoelectronics, piezoelectronics, cryoelectronics, and the development and manufacture of resistors.
Dielectric electronics deals with the electronic processes that occur in dielectrics—particularly in thin dielectric films—and the use of such processes in, for example, the development of dielectric diodes and capacitors. Magnetoelectronics makes use of the magnetic properties of matter to control the flow of electromagnetic energy by means of ferrite isolators, circulators, and phase shifters and to develop memories, including those based on ferromagnetic domains.
Acoustoelectronics and piezoelectronics deal with the propagation of acoustic surface and body waves, the variable electric fields that such waves generate in crystalline materials, and the interaction of the fields with electrons in devices with a piezoelectric semiconductor structure, such as quartz frequency stabilizers, piezoelectric filters, ultrasonic delay lines, and acoustoelectronic amplifiers. Cryoelectronics, in which the changes brought about in the properties of solids by extremely low temperatures are studied, involves the construction of low-noise microwave amplifiers and oscillators and ultrahigh-speed computers and memories, as well as the design and manufacture of resistors.
Quantum electronics. The most important application of quantum electronics is the development of lasers and masers. Quantum electronics devices serve as the basis of instruments used for the accurate measurement of distances (range finders), quantum frequency standards, quantum gyroscopes, optical-frequency multichannel communication systems, long-range space communication systems, and radio astronomy. The powerful action of laser radiation on matter is made use of in industry. Lasers also find application in biology and medicine.
Electronics is in a stage of intense development. New fields of electronics are evolving, and new areas of application in the current fields are being found.